As you watch Cam Newton face off against Peyton Manning later today, you might be thinking about their respective passing games, the strength of their offensive lines or whether hearing Coldplay during halftime will drain their will to play — or live.

Sports Illustrated journalist L. Jon Wertheim will have at least one other consideration in mind: whether Newton and Manning are better looking than their teammates.

“This is Your Brain on Sports,” Wertheim’s new book with psychologist Sam Sommers, takes a scientific approach to many of the quirks that guide athletes and sports fans alike, seeking to explain phenomena such as why we go crazy for T-shirt cannons (the power of “free”), or why watching rival teams lose makes us as happy as watching our own teams win (these events hit the brain’s pleasure centers in similar ways and with equivalent intensity).

One of the theories Wertheim and Sommers take on is whether quarterbacks are better looking than other players. Seeing Tom Brady with supermodel wife Gisele Bündchen, one might think the question’s been answered. But Wertheim and Sommers applied science to it, and what they found was surprising.

They cropped photos of all 32 NFL starting quarterbacks at the neck, so no uniform was visible, then did the same for wide receivers and defensive backs. They selected 100 people at random and asked them to rate the attractiveness of each face on a scale of 1 to 10.

Wertheim was shocked to find that quarterbacks ranked dead last. Asking a different 100 people and substituting linebackers for defensive backs produced the same result.

Wondering if “there was something unusual about the NFL QBs class of 2014,” they ran a third study using college quarterbacks from 20 random Division I schools. Again, the quarterbacks finished third.

The central question shifted. If quarterbacks are no better looking than their counterparts — and maybe even worse looking — then how did the position of quarterback get its leading-man image?

Wertheim and Sommers credit the halo effect, quoting economist Van Gilder as saying, “Socially, we’ve been trained to think that the quarterback is the most beautiful person on the team.”

They cite a study from the University of Michigan where two groups of students watched different videos of the same professor. In one, he “came across as warm and personable”; in the second, he “was scripted to come across much colder.”

Not only did those who watched the first video find the professor more likable, but they also gave higher scores to his nonverbal mannerisms, his French accent, and his physical attractiveness. “The friendly professor,” the authors write, “was rated as significantly better looking than the unfriendly professor. Even though they were the same guy.”

To test this effect, Wertheim and Sommers added a question to their photo array about the strength of the players’ leadership skills. The results were “pretty remarkable.”

They found that while quarterbacks may not cut it in terms of attractiveness, their faces had them rated the strongest leaders.

The authors conducted the survey again, this time dropping the attractiveness question and asking instead about leadership, intelligence, confidence, poise and social skill. Based on the photos alone, quarterbacks scored highest in all categories except confidence. And when combined into a comprehensive score of “perceived leadership quality, the quarterbacks’ superiority was statistically significant.”

‘Socially, we’ve been trained to think that the quarterback is the most beautiful person on the team.’

How was this so? For the answer, the authors turned to Nick Rule, “a psychologist who specializes in nonverbal behavior and appearance-related cues.”

“All of this has to do with our ability to perceive meaningful information from the social environment,” said Rule. “We’re constantly trying to evaluate whether something is going to be good or bad for us. Out of this has been born this ability to be really sensitive to all these little cues about how someone might behave toward us.”

Studies have produced similar results regarding the appearance of politicians. In one, people viewed head shots of congressional opponents for just one second each, then declared who they found “more competent.” Across more than 600 races, the House candidate picked as “more competent” won 67% of the time; in the Senate, 72%.

Rule said that not only has he seen similar results with corporate CEOs, but that facial appearance predicted how successful they were. “These perceptions scale with the amount of profit that a company makes,” he said.

Wertheim and Sommers, then, wanted to see if the results would be the same for quarterbacks and found that they were. Comparing the perceived leadership qualities they tested against actual results — “wins minus losses as a starter,” and their QB rating — they found that “our respondents ratings of a QB’s leadership qualities correlated positively — and statistically significantly — with both outcome variables. In other words, the more a QB looks like a leader, the more successful his actual track record tends to be.”

Why is this the case? The answer is a combination of two factors. For one, “We humans are surprisingly good at picking up the subtle facial and nonverbal cues that tell us something meaningful about other people’s social skills.”

Second, there’s the self-fulfilling prophecy factor, in that we are “surprisingly consistent in how we jump to conclusions about other people based on [their looks], and then we treat them in a way that brings out the tendencies we expect.”

“You’ve got a bunch of 8-year-olds on a football field,” says Rule. “At first, you’re arbitrarily picking who’s going to play where — mostly, it’s by body size. But for the ones who don’t clearly look like linemen, you’re going to pick the kid who seems like he’s the right one [to play quarterback]. Whether or not he does well at first, he gets plenty of practice being the quarterback. By high school he is a quarterback. And it goes on from there.”